Configuring service clients for the AWS SDK for PHP Version 3 externally

Many configuration settings can be handled outside of your code. Most configuration settings can be set as either environment variables or in a separate shared AWS config file. The AWS shared config file can maintain separate sets of settings, called profiles, to provide different configurations for different environments or tests. For a complete discussion of the AWS shared config and credentials files, see the AWS SDKs and Tools Reference Guide.

Most environment variables and shared config file settings are standardized and shared across AWS SDKs and tools to support consistent functionality across different programming languages and applications.

To see all the all settings that the SDK can resolve from the environment variables or configuration files, see the Settings reference in the AWS SDKs and Tools Reference Guide.

Configuration provider chain for client configuration

The SDK checks several places (or sources) to find configuration values.

Besides this general configuration chain, the AWS SDK for PHP Version 3 also uses specialized provider chains including the credentials provider chain and the AWS Region resolution chain. These specialized chains add additional providers that take into account the environment that the SDK is running in. For example, in a container or an EC2 instance.

Create a service client configured using external settings

You need to create a service client in your application to talk to an AWS service. Service clients are your essential connection to AWS services, handling all the complex communication details so you don't have to worry about them. They take care of important tasks like security, error handling, and retries automatically, letting you focus on building your application rather than dealing with technical complications.

Construct a service client using a constructor with no parameters

If all configuration settings that you need are coming from external sources, you can create a service client by using an empty constructor:

require 'vendor/autoload.php';

use Aws\S3\S3Client;

$s3 = new S3Client([]);

The previous code snippet creates an S3Client instance. During creation, the SDK looks through the configuration provider chain for settings. Once the SDK finds a setting value, it uses the value.

The default AWS Region provider chain and the default credentials provider chain will also be used in the creation process. Somewhere in the chain, the SDK must resolve the AWS Region to use and find settings that enable it to retrieve credentials for signing requests. If the SDKs files to find those values, the client creation fails.

AWS SDK for PHP Version 3 environment variables

Beyond the cross-sdk settings supported by most AWS SDKs, the AWS SDK for PHP Version 3 works with the following environment variables: